Description Usage Arguments Details Value Author(s) References See Also Examples

Calculate changes in right ascension and declination due to nutation of the Earth's rotation

1 | ```
co_nutate(jd, ra, dec)
``` |

`jd` |
Julian Date [scalar or vector] |

`ra` |
right ascension, in degrees (scalar or N-vector) |

`dec` |
declination, in degrees (scalar or N-vector) |

Calculates necessary changes to right ascension and declination due to the nutation of the Earth's rotation axis, as described in Meeus (1991), Chap 23. Uses formulae from the Astronomical Almanac (1984) and does the calculations in equatorial rectangular coordinates to avoid singularities at the celestial poles.

`d_ra` |
corrections to ra due to aberration, in arcseconds (must then be added to ra to get corrected values). |

`d_dec` |
corrections to dec due to aberration, in arcseconds (must then be added to dec to get corrected values). |

`eps` |
true obliquity of the ecliptic, in radians |

`d_psi` |
nutation of the longitude of the ecliptic |

`d_eps` |
nutation in the obliquity of the ecliptic |

Written Chris O'Dell (2002)

R adaptation by Arnab Chakraborty (June 2013)

Meeus, J., Astronomical Algorithms, Willmann-Bell, 1991

1 | ```
co_nutate(2456469.5,253.215,-32.449)
``` |

```
$d_ra
[1] 16.20117
$d_dec
[1] 5.262275
$eps
[1] 0.4090281
$d_psi
[1] 12.85696
$d_eps
[1] -7.038528
```

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